Geoscience Australia Sentinel-2A MSI NBART Collection 3 - DEA Surface Reflectance NBART (Sentinel-2A MSI)

Background:This is a sub-product of DEA Surface Reflectance (Sentinel-2A MSI) - Geoscience Australia Sentinel-2A MSI Analysis Ready Data Collection 3. See the parent product for more information.Reflectance data at top of atmosphere (TOA) collected by Sentinel-2A MSI sensors can be affected by atmospheric conditions, sun position, sensor view angle, surface slope and surface aspect.Surfaces with varying terrain can introduce inconsistencies to optical satellite images through irradiance and bidirectional reflectance distribution function (BRDF) effects. For example, slopes facing the sun appear brighter compared with those facing away from the sun. Likewise, many surfaces on Earth are anisotropic in nature, so the signal picked up by a satellite sensor may differ depending on the sensor’s position.These need to be reduced or removed to ensure the data is consistent and can be compared over time.What this product offers:This product takes Sentinel-2A MSI imagery captured over the Australian continent and corrects the inconsistencies across the land and coastal fringe. It achieves this using Nadir corrected Bi-directional reflectance distribution function Adjusted Reflectance (NBAR).In addition, this product applies terrain illumination correction to correct for varying terrain.The resolution is a 10/20/60 m grid based on the the ESA level 1C archive.Applications:- The development of derivative products to monitor land, inland waterways and coastal features, such as: - urban growth - coastal habitats - mining activities - agricultural activity (e.g. pastoral, irrigated cropping, rain-fed cropping) - water extent- The development of refined information products, such as: - areal units of detected surface water - areal units of deforestation - yield predictions of agricultural parcels- Compliance surveys- Emergency management

背景：
本产品是DEA地表反射率（Sentinel-2A MSI）——澳大利亚地球科学局Sentinel-2A MSI分析就绪数据集3的子产品。更多信息请参见母产品。

Sentinel-2A MSI传感器采集的大气顶层反射率数据（TOA）会受到大气条件、太阳位置、传感器视角、地表坡度及地表坡向的影响。

地形变化的地表会通过辐照度和双向反射分布函数效应（BRDF）给光学卫星图像带来不一致性。例如，向阳坡比背阳坡显得更亮。同样，地球上许多地表本质上具有各向异性，因此卫星传感器捕获的信号会因传感器位置而异。

需减弱或消除这些影响，以确保数据的一致性及时间上的可比性。

产品优势：
本产品针对覆盖澳大利亚大陆的Sentinel-2A MSI影像，校正陆地及沿海边缘区域的不一致性。这一校正通过天底点校正双向反射分布函数调整反射率（NBAR）实现。

此外，本产品还应用地形光照校正以消除地形变化的影响。

分辨率为基于欧洲空间局（ESA）1C级存档的10/20/60米网格。

应用场景：
- 开发衍生产品以监测陆地、内陆水道及海岸特征，例如：
- 城市扩张
- 海岸栖息地
- 采矿活动
- 农业活动（如牧场、灌溉作物、雨养作物）
- 水域范围
- 开发精细化信息产品，例如：
- 探测到的地表水面积单元
- 森林砍伐面积单元
- 农业地块产量预测
- 合规性调查
- 应急管理